Propynyl sulfenamides



contain a nitro, chloro, group substituted in the benzene ring, and R represents hydrogen, an alkyl, aralkyl or a taining 40 parts (0.25 mole) of solution. Thesolution preferably is was t then extracted ether was then removed 2,875,208 PROPYNYL SULFENAMIDES John J. DAmico, Nitro, Chemical Company, Delaware No Drawing. Application December 28, 1956 Serial No. 631,070

7 Claims. (Cl. 260-6066) W. Va., assignor to Monsanto St. Louis, Mo., a corporation of The present invention relates to a class of new chemrubber as will hereinafter be ducing the new products. The products may be described broadly as thiazolesulfenamides and can be schematically -repre'sented by the general formula XS-N OHr-OEOH wherein X represents an aryl thiazole nucleus which may phenyl, methoxy, alkoxy or alkyl cycloalkyl group. Preferably, the alkyl group mentioned contains from one to and including five carbon atoms, such as methyl, ethyl,

prcipyl, isopropyl, butyl, isobutyl, and amyl. groups. A preferred method of obtaining the new products is set forth in the following examples of the invention.

EXAMPLE l.-PRODUCT A N-isopropyl-N- (2-pr0pynyl) -2-benzothiazolesulfenamide A solution of the sodium salt of Z-mercaptobenzothiazole was prepared by dissolving 43 parts (0.25 mole) of 97% mercaptobenzothiazole in 50 parts of Water consodium hydroxide filtered toremove any insoluble particles therefrom. Thereupon.97;2 parts '(110 mole) of N-isopropyl-2-propynylamine were added over a period of time While agitating the mixture. When all of the amine had been added, 60 parts of 25% sulfuric acid were slowly added with stirring until thorough admixture resulted. Next 22.3 parts (0.3 mole) of sodium hypochlorite contained in 150 parts of water were added slowly while maintaining the temperature 'of-the mass between 25-30' C. by suitable cooling means as required. Agitation was continued for about an hour after all the hypochloritehad been added. Then 2 parts .of sodium lsulfite were added to remove any. unreacted oxidizing agent fromthe reaction. The reaction-mixture with. a-suitab1e solvent, such as ether, in which any by-product dior polysulfides are insoluble,

, the extract was-filtered and the ether. solution washed with water to neutrality of the water washings. The

extract was then dried by means. of anhydrous sodium sulfate 'to'remove any water. droplets present and the h 7 in vacuo at a temperature below C." A semi-solid which was dark amber in color was obtained in 54.8% yield. The product was soluble in acetone, :ether, benzene,chloroform,. ethanol, ethyl acetate, and heptane; Theexpected product, of empirical was confirmed by analysis for nitropresent as compared .UPitt Stews P rO C H ClN S as is evident from under same conditions as was product A. tion of the .product as C H N S and ashamed in this 7 benzothiazole in place of 65 2 EXAMPLE 2.--PRODUCT B 5-chlora-N-isopropyl-N-(Z-propynyl) -2- benzothiazolesulfenamidle the same characteristics in solvents as the product of Example I. Identification of the product of this example was confirmed by analysis as possessing the formula the results that follow:

Percent Percent Found Theory nitrogen 9. 9. 44 chlorine 12. 41 11. 94

EXAMPLE 3.-PRODUCT C N-isopropyll-methyl-N-(Z-propynyl) -2- benzothiazolesulfenamide tween 2530C. Agitation was continued-for about an hour after all the reactants had been added. Thereupon, were added to destroy any residual oxidizing agent present. After cooling to a maximum temperature of 25 C. the mass was extracted with ether, the ethereal solution was filtered, washed with waterto neutrality, dried and the solvent removed as described in Example 1. An aniber colored oil was obtained in 69.5% yield. This .product was soluble Identificaexample was confirmed by analysis which'produced as results:

Percent Percent Found Theory NM nitrogen 9.91 10.15

EXAMPLE 4.-PRODUCT D fi-ethoxy-N-isopropyl-N-(Z-prqpynyl) -2- benzotlziazolesulfenamide Again proceedingas described in Example 3 hereof, but usin'gj52.8:parts (0.25 mole) of 6-ethoxy mercaptothe 4-methyl mercaptobenzothiazcle used in'the said example and maintaining the reaction temperature at 45-50 C., there was obtained a cream colored'solid melting at 91 C. after recrystallization from ethyl alcoholand displaying the same characteristics in solvents as pointed 'out in the three previous examples. The "product was identified "'as ihe fenamide.

one named in this example by analysis, confirming the formula C H N OS as is shown from the results:

Percent Percent Found Theory Further examples of the new compounds comprise N- methyl N (2 propynyl) 2 benzothiazolesulfenamide, N ethyl-N-(Z-propynyl)-2-benzothiazolesulfenamide, N-isobutyl-N-(2-propynyl)-2-benzothiazolesulfenamide, N-isoamyl-N-(Z-propynyl)-2-benzothiazolesulfenamide, N-benzyl-N- (2-propynyl) -2-benzothiazole-sulfenamide, N-cyclohexyl-N-(2-propynyl)-2-benzothiazolesul fenamide and N-allyl-N-(2-propynyl)-2-benzothiazolesul- Most of the intermediates required have been described and others may be prepared by application of known principles. For example, N-isopropyl-Z-propynylamine may be prepared as follows: To a stirred solution containing 591 grams (10.0 moles) of isopropylamine and 400 ml. of water, moles of 3-bromo-1-propyne was added dropwise at 47-65 C. over a three hour period. The stirred reaction mixture was heated at 60-70 C. for four hours. After cooling to C., 500 grams of 50% aqueous sodium hydroxide was added over a ten minute period. The reaction mixture was stirred for one additional hour and the sodium halide was removed by filtration. The top organic layer was dried over caustic and excess isopropylamine was removed by distillation. The distillation of the residue through a 4-foot VigreuX-type column gave N-isopropyl-Z-propynylamine, B. P. 110- 111 C., n 1.4230, analyzing 14.54% nitrogen as compared to 14.42% calculated for C H N.

The products of the present invention as described here "inbefore have been found effective as accelerators of the vulcanization of rubber as are shown by the following examples which are typical of the class of products. Mixes were prepared in the well known manner according to the recipes shown below:

Stock A B O Smoked sheets rubber Carbon black (Philblack O). Zinc oxide Stearic acid Saturated hydrocarbon softener Sullur.

Antioxidant 1. Product A 0. 5 Product B. 0. 5 Product D 0. 5

The stocks so compounded were cured in the usual manner by heating in a press for diiferent periods of time at 144 C. The physical properties of the vulcanizates are set forth below:

' Additionally, another characteristic test was carried out in which product A was tested in a typical tread stock,

additionally containing a retarder of vulcanization. As the formulation there was employed a mix comprising "100 parts'of smoked sheet rubber, 50 parts of carbon black (Philblack O), 5 parts of zinc oxide, 3 parts of stearic acid, 3 parts of saturated hydrocarbon softener, 2.5 parts of sulfur, 0.5 part of product A, and 1.5 parts of N-nitroso diphenylamine, a retarder particularly efiec tive with sulfenamide accelerators. The stock was cured for 45 minutes in a press at 144 C. and compared with a similarly prepared and cured stock but containing, in place of product A, an equal weight of a commercial sulfenamide delayed action accelerator. The test results obtained were as follows:'

TAB LE 11 Commercial sulfenamlde Modulus of Elasticity in lbs/in; at 300% E ngat n Tensile at; break in lbs/in. Mooney scorch at 121 0 X-S-N' CH-GEOH wherein R represents an alkyl group containing not more than five carbon atoms and X represents the benzothiazolyl radical.

3. As a new compound a propynyl-Z-benzothiazolesulfenamide having the structure wherein R represents a hydrocarbon group containing not more than six carbon atoms at least one of which is saturated and X represents an aryl thiazole radical the aryl group of which consists of carbon and hydrogen, is a member of the benzene series and contains not more than 12 carbon atoms.

4. As a new compound N-isopropyl-N-(2-propynyl)- 2-benzothiazolesulfenamide.

5. As a new compound S-chloro-N-isopropyl-N-(2- propynyl)-2-benzothiazolesulfenamide.

6. As a new compound N-isopropyl-4-methyl-N-(2- propynyl)-2-benzothiazolesulfenamide. l

7. As a new compound 6-ethoxy-N-isopropyl-N-(2- propynyl)-2-benzothiazolesulfenamide.

References Cited in the file of this patent UNITED STATES PATENTS Prottxiuct Benzothlazole- 

1. AS A NEW COMPOUND A PROPYNY-2-BENZOTHIAZOLESULFENAMIDE HAVING THE STRUCTURE 